Rockwell Automation 1440-DYN02-01RJ XM Dynamic Measurement Module - Manuel (Page 142)

142 Publication ICM-UM002F-EN-E - March 2013
Appendix B CIP Objects
The Waveform Data structure contains an array of values that, taken together,
are the output of the sampling performed by the Spectrum/Waveform
Measurement Object on the input signal. The Waveform Data array values are
normalized and must be converted to floating point to obtain the true values.
The total size of the Waveform Data structure in DWORDs is: 3 + (Number
of Waveform Points
/ 2)
The Waveform Data is an array of INT (16-bit signed integers ranging from
-32768 to 32767). The number of INTs in the Waveform Data array is equal to
the Number of Waveform Points. To convert the normalized Waveform
Data into floating point values, use the following equations:
Where Float Data n is the value for the nth waveform point, and 0
≤ n ≤
Number of Waveform Points .
The Get_Spectrum_Chunk and Get_Waveform_Chunk services use the same
request and response parameters.
Table B.41 Waveform Data Structure
Byte (DWORD)
offset within
structure Structure Member Data Type Description
0 (0) Number of
Waveform Points UDINT Number of points in the waveform data. This should be
equal to the
Number of Waveform Points attribute
setting. It is provided within this structure to assist in
determining the size of the structure.
4 (1) Period REAL The period of the waveform.
This is the actual period of the waveform and may vary
from the
Period attribute setting.
8 (2) Amplitude
Reference REAL Normalization factor
This factor is used to convert the normalized array data
into floating point values.
12 (3) Normalized Value
Array Array of INT The normalized waveform data points
These must be converted to floating point values using
the Amplitude Reference value.
Float Data
n
Amplitude Reference
Normalized Data
n
32768
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